Creating CSS APIs without JavaScript With the datasette-css-properties plugin

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Simon Willison has a project called Datasette, an open source multi-tool for exploring and publishing data. I’m not sure I’m qualified to explain it, but it’s like a tool to make handling data easier and doing more — through the web — with data you have. Like making that data queryable and giving it an API.

I would think, typically, you’d get the results of an API call against your data in something useful, like JSON. But Simon made a plugin that outputs the results as CSS custom properties instead, and blogged it:

It’s very, very weird—it adds a .css output extension to Datasette which outputs the result of a SQL query using CSS custom property format. This means you can display the results of database queries using pure CSS and HTML, no JavaScript required!

Here’s what I said just recently in “Custom Properties as State”:

This makes me think that a CDN-hosted CSS file like this could have other useful stuff, like today’s date for usage in pseudo content, or other special time-sensitive stuff. Maybe the phase of the moon? Sports scores?! Soup of the day?!

And Simon is like, how about roadside attractions?

My brain automatically worries about the accessibility of that, but… aren’t pseudo-elements fairly and reliably read in screen readers these days? You still can’t select the text though, or find-on-page, which are both usability and accessibility issues, so don’t consider this like a real thing that you really do for production work with unknown users.

His blog post demonstrates a slightly more dynamic example where the time of day outputs a different color. That makes me think of @property and declaring types for custom properties. I think this gets a smidge more useful when you can use the values that come back as specific syntaxes.